A structure of a general security lamp of related art may be seen in Korean Utility Model No. 20-2008-0005178 (Title: Electric lamp for street lighting fixture; referred to as “cited invention 1”), which is illustrated in FIG. 1.
As disclosed therein, in the related art, a metal halide lamp is coupled to the Edison socket by rotating a base thereof, and if the metal halide lamp is required to replace, the base is rotated in the opposite direction to be removed and replaced with a new lamp. To this end, a diameter of the metal halide lamp has to be less than a distance D between the center of the Edison socket and a reflector, as illustrated in FIG. 1. However, a security lamp or a street lamp using an LED has recently been used widely, which is configured by assembling a large number of LEDs on a PCB. Specifically, the large number of LEDs are dispersed and arranged on the PCB, which gives rise to the increase in the width thereof.
Accordingly, a width of the plate-shaped LED is several times greater than the distance D, and thereby, the plate-shaped LED may not be mounted in the Edison socket. Thus, the Edison socket that is mounted in the existing luminaire can't be used, and thus, a problem occurs in which there is a construction work and an economic burden for replacing the luminaire itself.
In order to solve such a problem, an LED lamp has been manufactured in a narrow and long shape similar to an appearance of a metal halide lamp such that a socket and a housing of a security lamp or a street lamp may be used as it is, and an example thereof is illustrated in FIGS. 3 and 4 of Korean Patent No. 10-1709728 (Title of Invention: LED lighting apparatus; referred to as “cited invention 2”) and Korean Patent Publication No. 10-2018-0114476 (Title of Invention: LED lighting apparatus; referred to as “cited invention 3”).
In the cited inventions 2 and 3, a printed circuit board is formed to have a hollow pillar structure, and an LED chip is disposed on the printed circuit board, and the printed circuit board is put in the same cover member as a metal halide lamp to allow power to be supplied thereto, and thereby, a radius of the LED lighting device may be less than or equal to the distance D between the center of the Edison socket and the reflector. Since the existing metal halide lamp may be inserted into a socket of a housing to be used, the cited inventions 2 and 3 have an advantage that may solve an economic burden of replacing the LED lamp and the whole housing and Hassle due to a replacement construction work. Meanwhile, the cited inventions 2 and 3 have a problem in which since a space to emit heat generated during the LED lighting process is hard to secure, a failure rate is high due to a thermal damage of an LED in summer or the like. Further, since the LED has to be installed on a pillar of a limited area having a diameter smaller than the bulb of the metal halide lamp, the number of installable LEDs is limited, resulting in insufficient light quantity. In addition, the cited Invention 2 and 3 have a problem in which since the LED is installed around the hollow pillar, the LED emits light in all directions, and since the LED light has a high straightness, a light emission efficiency is reduced in the process of collecting light in a down direction which is a direction necessary for a security lamp or a street lamp.